Furthermore, you don't just have the two categories of "programs that use libc" and "programs that wing it", but also the third category of "programs that use shell32". Windows ships with two cmdline->argv implementations - one in MSVCRT and the other in shell32. Both are first-party but don't split args the same in all cases.
> CommandLineToArgvW has a special interpretation of backslash characters when they are followed by a quotation mark character ("). This interpretation assumes that any preceding argument is a valid file system path, or else it may behave unpredictably.
(Nothing to do with unicode. I haven't got a Windows machine to test, but I assume WinMain will behave the same as main wrt quotes and spaces.)
(Note that Rust doesn't use CLTAW any more; it switched to "winging it" ie its own implementation. Among other things, this allowed it to drop the dependency on shell32, which is useful for running compiled binaries in nanoserver containers.)